Zirconia nanomaterials, usually doped with trivalent ions, are widely used in the development of ceramic materials, sorbents, catalyst supports and biocompatible luminescent nanoprobes. Fluorescent zirconia-based nanoparticles, with and without arsenic and/or cysteine, were prepared at room temperature by a precipitation procedure in 1,2-ethanediol aqueous solutions. The prepared zirconia nanoparticles were characterized at several temperatures by XRD, SEM/ED-XRS, Raman spectroscopy, FT-IR, optical spectrophotometry and fluorescence microscopy. The zirconia-base nanoparticles treated at 873 K showed a pure tetragonal phase with crystallite sizes around 18 nm. The presence of arsenic and cysteine in the ZrO 2 nanoparticles facilitated the emission of fluorescence, even after thermal treatments at 873 K. However, the As-doped and Cyst-capped nanomaterial treated at 1373 K produced less-fluorescent monoclinic zirconia nanoparticles, with crystallite sizes larger than 20 nm. Comments about the stabilization mechanism of the crystallographic phases of the zirconia nanoparticles were also outlined.